_Designing C++ Interfaces to C-Language Libraries_
by Larry E. Baker, Jr.


Listing One
typedef struct _HT_LIST {		// list of pointers
  struct _HT_LIST *next;
  void            *item;
} HT_LIST;

typedef struct _HASH {		// array of lists, hash/compare functions
  int   size;
  HT_LIST         **buckets;
  int             (*hash)(void *);
  int             (*compare)(void *, void *);
} HASHTABLE;


Listing Two
HASHTABLE *
htcreate(              		/* create a new hash table */
  int size,                            /* # of buckets in table */
  int (*hash_function)(void*),         /* user hash function */
  int (*search_function)(void*,void*)  /* user search function */
);

int
htdestroy(                       /* destroy hash table */
  HASHTABLE * hash_table,              /* existing hash table */
  int   flags                          /* HT_FREE_REC|0 */
);

int
htinsert(              		/* insert a new entry */
  HASHTABLE   * hash_table,            /* existing hash table */
  void    * record                     /* record ptr to insert */
);

int
htdeleterec(                     /* delete a table entry */
  HASHTABLE * hash_table,              /* existing hash table */
  void    * record,                    /* record or template */
  int   flags				      /* HT_FREE_REC|0 */
);

int
htsearch(                        /* search and/or remove */
  HASHTABLE * hash_table,              /* existing hash table */
  void    * templ,                     /* search template */
  void    ** record,                   /* &ptr for record found */
  int   flags                          /* HT_FREE_REC|HT_REPLACE|HT_DELETE|0 */
);

void
htstats(                       	/* print out hash tbl stats */
  HASHTABLE * hash_table               /* existing hash table */
);

/* for htwalk, note that the function takes two arguments.  The    */
/* first is a pointer to the object found in the hash table; the   */
/* second is an argument passed in the void * arg pointer.         */
/* this is done so an argument can be passed "through" the ht walk */
/* function to the user-supplied "func" function.                  */

void
htwalk(                        	/* walk through the table */
  HASHTABLE * hash_table,              /* existing hash table */
  void  (*func)(void *, void*),        /* function to apply */
  void  * arg                          /* user argument to function */
);


Listing Three
template <class T> class HTable
{
  public:
	 HTable(
		int size,
		int destroyFlags,
		int (*hashFunction)(T*),
		int (*compareFunction)(T*, T*)
	 );
	 HTable(HASHTABLE * ht);
	 ~HTable();

	 int insert(T& item);
	 int deleterec(T& itemTemplate, int flags);
	 int search(T& itemTemplate, T ** foundItem, int flags);
	 void stats();
	 void walk(void (*walkFunction)(T&, void*), void * walkArg);

	 int rc;

  protected:

	 HASHTABLE * ht;
	 int dFlags;

	 static void HTable::walkDestructor( T * pT, void * arg);
};



